This invention relates to a method of vacuum-sealing such vacuum articles as vacuum display tubes and the like.
Such a vacuum article is generally provided with an exhaust pipe for evacuating the article by connecting it with a vacuum pump. Such exhaust pipe, however, not only increases the dimension of the article but also decreases the degree of attainable vacuum due to low exhaust conductance caused by a comparatively long length of the pipe.
The exhaust pipe of a flat type vacuum display tube is connected to the flat substrate, spacer or boat shaped face glass plate of the tube by frit glass. After evacuation, the exhaust pipe is chipped off. Accordingly, the remaining portion of the exhaust pipe projects from the display tube thereby requiring an additional space for mounting the display tube. To decrease the space occupied by the exhaust pipe, it is necessary to decrease its diameter. Furthermore, as it is necessary for the exhaust pipe to have a definite length for connecting it to vacuum pump, the exhaust conductance is decreased. For this reason, the degree of vacuum in the vacuum display tube is much lower than the degree attainable by the evacuation pump.